Issue with math in physics problem?

  • Thread starter fightboy
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In summary, the solutions manual simplified the expression by canceling out the ##R_E^2## terms and multiplying by a factor of ##\frac{5}{2}##, resulting in the second equation. However, the ambiguity in the fractions and the lack of explanation in the manual may cause confusion for some.
  • #1
fightboy
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Ok so for the problem I'm mainly having trouble with setting up one of the equations.
The solutions manual jumped from:
ωiz([(2/5mERE2)/(2/5mERE2) + (2/3mdebrisRE2)]-1)
to:
ωiz([mE/(mE + (5/3mdebris))]-1)

I placed the brackets to clearly separate the fraction from the -1. Anyways I'm having trouble seeing how the math is done to get from the first equation to the second equation, how was it simplified? If anyone is confused on how i wrote the problem please just ask! Thanks!
 
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  • #2
fightboy said:
Ok so for the problem I'm mainly having trouble with setting up one of the equations.
The solutions manual jumped from:
ωiz([(2/5mERE2)/(2/5mERE2) + (2/3mdebrisRE2)]-1)
to:
ωiz([mE/(mE + (5/3mdebris))]-1)

I placed the brackets to clearly separate the fraction from the -1. Anyways I'm having trouble seeing how the math is done to get from the first equation to the second equation
These aren't equations - they are expressions.

Inside the parentheses you have (2/5mERE2)/(2/5mERE2), which is just 1.

The fractions you wrote are ambiguous, which doesn't change what I wrote above.
Is the numerator ##\frac{2}{5}m_ER_E^2##
or is it ##\frac{2}{5m_ER_E^2}##?
fightboy said:
, how was it simplified? If anyone is confused on how i wrote the problem please just ask! Thanks!
 
  • #3
Mark44 said:
These aren't equations - they are expressions.

Inside the parentheses you have (2/5mERE2)/(2/5mERE2), which is just 1.

The fractions you wrote are ambiguous, which doesn't change what I wrote above.
Is the numerator ##\frac{2}{5}m_ER_E^2##
or is it ##\frac{2}{5m_ER_E^2}##?
The numerator is ##\frac{2}{5}m_ER_E^2##. I get that ##\frac{2}{5}m_ER_E^2##/##\frac{2}{5}m_ER_E^2## is equal to 1, I am mainly confused on how (2/3mdebrisRE2) became (5/3mdebris) or if the manual made a mistake.
 
  • #4
If you put an extra set of parentheses in the original expression, the ##R_E^2##s cancel and you can multiply everything by ##\frac{5}{2}## to get $$\frac{\frac{2}{5}m_ER_E^2}{\frac{2}{5}m_ER_E^2+\frac{2}{3}m_{\text{debris}} R_E^2}=\frac{m_E}{m_E+\frac{5}{3}m_{\text{debris}}}$$
 
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  • #5


I understand that math can be challenging and it's important to have a clear understanding of the equations we use in physics. In this case, it seems like there may have been a step or two missing in the solutions manual. It would be helpful to see the entire problem and the steps leading up to the first equation in order to fully understand the simplification process.

One possible explanation for the simplification could be that the term (2/5mERE2) was factored out and then the remaining terms were combined to create the second equation. However, without more context it is difficult to say for sure.

It's always important to double check your work and make sure you understand each step in a problem. If you are still having trouble, I would suggest reaching out to your teacher or a tutor for clarification. Additionally, there are many online resources and forums where you can ask for help with specific physics problems. Keep persevering and seeking understanding, as that is a key aspect of being a successful scientist.
 

What is the most common issue students face with math in physics problems?

The most common issue students face with math in physics problems is the lack of understanding of the mathematical concepts and equations used in the problem. Many students struggle with applying the correct equations and manipulating the variables in order to solve the problem correctly.

How can I improve my math skills for solving physics problems?

To improve your math skills for solving physics problems, it is important to practice regularly and seek help from a teacher or tutor if you are struggling with a particular concept. It is also helpful to review fundamental math concepts, such as algebra and trigonometry, as these are commonly used in physics problems.

What should I do if I am stuck on a physics problem that involves complex math?

If you are stuck on a physics problem that involves complex math, it is important to step back and break down the problem into smaller, more manageable parts. You can also try looking for similar problems in your textbook or online to see how they are solved. Don't be afraid to ask for help from a teacher or classmate if you are still struggling.

Why is it important to have a strong understanding of math in physics?

A strong understanding of math is crucial in physics because the subject relies heavily on mathematical equations and concepts to explain and solve physical phenomena. Without a solid foundation in math, it can be difficult to fully comprehend and apply the principles of physics.

What resources are available to help me with math in physics problems?

There are many resources available to help you with math in physics problems, such as textbooks, online tutorials, and study groups. Your teacher or professor may also offer extra help sessions or be available for one-on-one assistance. Additionally, there are numerous apps and websites that provide practice problems and explanations for various math and physics concepts.

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